1. Field of the Invention
The present invention relates to a method, system and network element implementing a transmission using a transport protocol. In particular but not restricted thereto, the invention relates to a Fast Recover algorithm to improve performance of a reliable transport protocol, for instance SCTP (Stream Control Transmission Protocol) or TCP (Transmission Control Protocol), over a wireless link.
2. Description of the Related Art
SCTP (Stream Control Transmission Protocol) is a reliable transport protocol, which has been approved by the IETF (Internet Engineering Task Force) as a Proposed Standard [RFC2960]. Congestion control algorithms used by SCTP are based on [RFC2581].
A current problem is that standard transport protocols, e.g. SCTP, are designed for wired links. They interpret all packet losses as the result of network congestion and the corresponding congestion control process (algorithm), e.g. Fast Retransmission, will be triggered accordingly. However, in wireless links, there are quite many individual packet losses caused by link error or bit error. In this case, SCTP would be trapped into frequent Fast Retransmission processes caused by such individual packet losses and the congestion window would be restrained to a low level.
A lot of approaches have been proposed to enhance the performance of transport protocols in wireless network, such as:
I-TCP described in: A. Bakre and B. Badrinath: “I-TCP: Indirect TCP for Mobile Hosts. In Proceedings of the IEEE ICDCS'95, pages 136-143, 1995”;
M-TCP described in: Kevin Brown and Suresh Singh, “M-TCP: TCP for Mobile Cellular Networks”, in Proceedings of the ACM SIGCOMM Computer Communication Review, pages 19-43, 1997;
EBSN described in: Bikram S. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, “Improving Performance of TCP over Wireless Networks”, in Technical Report 96-014, Texas A & M University, 1996;
WTCP described in: Karu Ratnam and Ibrahim Matta, “Effect of Local Retransmission at Wireless Access Points on the Round Trip Time Estimation of TCP”, in Proceedings of IEEE 31st Annual Simulation Symposium '98, April 1998, or in: Karu Ratnam and Ibrahim Matta, “WTCP: An Efficient Mechanism for Improving TCP Performance over Wireless Links”, in Proceedings of the Third IEEE Symposium on Computer and Communications (ISCC '98), June 1998; or SNOOP described in: H. Balakrishnan, S. Seshan, E. Amir, and R. Katz, “Improving TCP/IP Performance over Wireless Networks”, in Proceedings of the 1st ACM Int'l Conf. On Mobile Computing and Networking (Mobicom), November 1995.
Most of these proposals need a Wired-Wireless Gateway to hide the wireless link feature. The Wired-Wireless Gateways (generally a base station) detect the loss, buffer some amount of data (e.g., to perform local retransmission, etc), and do some extra processing for each connection going through them.